U.S. Severe Weather Forecast (Coup d'œil sur la convection)

Day Three

acus01 kwns 310041 
Storm Prediction Center ac 310039 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0739 PM CDT Monday Mar 30 2015 

Valid 310100z - 311200z 

..no severe thunderstorm areas forecast... 

a few thunderstorms are possible this evening across the northeast 
Gulf Coast states. Isolated thunderstorms are possible late tonight 
mainly over southern Oklahoma into western Arkansas. 

A shortwave trough analyzed over the Carolina Gulf Stream will 
continue to progress eastward into the base of a larger-scale trough over 
the western Atlantic. Upstream of this feature...a southeastward-migrating 
perturbation will move from southern Manitoba into the upper Midwest 
tonight. Farther west...a lower-latitude middle-level low will shift eastward 
into Baja California California by daybreak while a potent shortwave trough is forecast 
to approach the Oregon/Washington coast late tonight. 

..northeast Gulf Coast states... 
The advection of middle-level dry air into the region according to 
water vapor imagery/radiosonde observation data and the lack of appreciable 
large-scale forcing for ascent should limit isolated storm activity 
going forward this evening. A thunderstorm or two is possible in vicinity of 
a diffuse frontal zone located over the region before nocturnal 
boundary-layer stabilization. 

..srn OK into western Arkansas... 
The possibility for a few showers and thunderstorms to develop will 
seemingly exist across primarily southern OK and into parts of western Arkansas 
late tonight as weak warm air advection is imposed on low-level northward-advancing 
moisture from northestern Texas and into southern OK. Conditional instability via 
a plume of 700 mb-500 mb lapse rates near 9 degree c per km over the Red River 
valley is resulting in 1000-2000 j/kg MUCAPE...but a Stout capping 
inversion and the absence of upper forcing will likely limit storm 

.Smith.. 03/31/2015 

Mesoscale Discussion

acus11 kwns 301811 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 301811 

Mesoscale discussion 0159 
National Weather Service Storm Prediction Center Norman OK 
0111 PM CDT Monday Mar 30 2015 

Areas affected...far southern Alabama...far southern Georgia...the Florida Panhandle 

Concerning...severe potential...watch unlikely 

Valid 301811z - 302045z 

Probability of watch issuance...5 percent 

Summary...the risk for isolated strong thunderstorms is increasing 
this afternoon...though ww issuance will not be needed. 

Discussion...low-level lapse rates are steepening S of a frontal 
zone and accompanying multi-layered clouds that visible imagery/surface 
observations highlight from central MS to portions of central/southern al/GA. 
Differential-heating-induced baroclinicity on the fringes of these 
clouds coupled with modest background frontal ascent are leading to 
recent agitation in cumulus fields in vicinity of far southern Alabama/far southwestern Georgia. Isolated 
deeper convection should Blossom from this activity during the next 
few hours owing to continued diurnal heating coupled with the 
grazing influence of midlevel ascent at the southern end of an eastern-Continental U.S. 
Migratory trough per water vapor loops. 

Modifications to rap forecast soundings to account for current surface 
observations indicate 500-1250 j/kg of MLCAPE -- enhanced by 
7-8-c/km lapse rates in the 700 mb-500 mb layer as sampled by upstream 12z 
Jan/lix radiosonde observations. With moderate westerly/west-northwesterly flow through the 
convective-cloud layer evident in vax/tlh vwps...relatively 
long/straight hodographs may favor splitting...marginal supercell 
storms with strong wind gusts and hail -- perhaps reaching severe 
levels on an isolated basis. However...with only modest low-level 
flow and related weak low-level convergence...and given only modest 
tropospheric moisture /pw around 0.75-1.00 inch per GPS 
imagery/...the overall coverage of robust updrafts with severe-thunderstorm 
potential will likely remain limited. 

.Cohen/Hart.. 03/30/2015 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 30808309 30308288 30088413 30428644 30828764 31218796 
31368740 30808309